A facsimile machine is an example of an image processing apparatus. The facsimile machine has to have both image reading capability and image printing capability, and further has to be as small as possible.
With this background, there is already an integrated image reading/writing head Y as shown in FIG. 16. The integrated image reading/writing head Y comprises a case 1 having an upper surface portion fitted with a transparent cover 19. Inside the case 1, a light source 3 for illuminating a reading line L provided on the transparent cover 19 and a lens 5 are provided. The case 1 has a bottom surface portion mounted with a substrate 4. The substrate 4A has an upper surface 40 and a back surface 41 respectively mounted with a plurality of sensor IC chips 2 each incorporating a plurality of light receiving elements 20 and a plurality of heating elements 60, linearly and longitudinally of the substrate 4. Further, the back surface 41 of the substrate 4 is also mounted with a plurality of drive IC chips 6 as part of a drive circuit for drive control of the heating elements 60.
As shown in FIG. 17, the substrate is provided with two connectors 8A, 8B for electrical connection with unillustrated external components. The connector 8A is electrically connected with the sensor IC chips 2 via a wiring pattern (not illustrated) formed in the upper surface 40 of the substrate 4. The connector 8B is electrically connected with the heating elements 60 and the drive IC chips 6 via a wiring pattern (not illustrated) formed in the back surface 41 of the substrate 4.
According to the integrated image reading/writing head Y constituted as above, as shown in FIG. 16, a document D is contacted onto the transparent cover 19 and fed by a platen roller P1. During this feeding process, a surface of the document D is illuminated by light from the light source 3. Light reflected by the surface of the document D is focused by a lens 5, forming an image of the document D on the array of the light receiving elements 80. Each of the light receiving elements 80 outputs read image data line by line. This output signal is taken out via the connector 8A. On the other hand, a thermosensible recording paper K is contacted onto each of the heating elements 60 and fed by a platen roller P2. During this feeding process, the drive circuit constituted by the drive IC chips 6 selectively drives the heating elements 60 based on data sent from outside via the connector 8B, thereby printing an image on the recording paper K line by line. If the integrated image reading/writing head Y of the above constitution is used, the facsimile machine can be made thinner than in the case where the reading head and the writing head are separated from each other.
However, the above facsimile machine has the following problems.
First, the two platen rollers P1, P2 are disposed so as to sandwich the whole of the integrated image reading/writing head Y. Thus, the entire assembly of the integrated image reading/writing head Y and the two platen rollers P1, P2 has a large dimension thickness-wise of the integrated image reading/writing head Y. Therefore, the thickness of the facsimile machine as a whole is still large.
Second, when manufacturing the integrated image reading/writing head Y, first, the sensor IC chips 2 must be mounted on the upper surface 40 of the substrate 4, and then the substrate 4 must be turned over in order to mount the heating elements 60 and the drive IC chips 6 on the back surface 41 of the substrate 4e. Further, wiring patterns relevant to these must be formed respectively in the upper surface 40 and the back surface 41 of the substrate 4. Therefore, productivity in the manufacture of the integrated image reading/writing head Y is low.
Third, there are many connectors, since the substrate 4 is provided with two connectors 8A, 8B. Therefore, productivity in the manufacture of the integrated image reading/writing head Y becomes even lower.